Core D. The Neuropathology Core performs diagnostic evaluations and quantitative analyses on brain tissue collected at autopsy of participants in the Mayo Alzheimer Disease Research Center (ADRC) and related projects, in particular the Alzheimer Disease Patient Registry (ADPR). The Core also provides support to research projects of the ADRC and to other investigators at the Mayo Clinic. The neuropathology data is communicated to the Biostatistics Core and to the National Alzheimer Coordinating Center (NACC). The specific aims of the NP Coreare: 1. Perform brain autopsies on participants of the Mayo ADRC in a timely fashion and according to protocol. 2. Provide neuropathologic evaluations and collect neuropathologic data using standardized methods for gross dissection and neurohistologic staining. a. Cooperate with neuroradiology in the acquisition of post-mortem MRI scans of hemi-brains. b. Dissect brains according to a standardized protocol, and photograph all sections. Score the severity of cerebrovascular pathology, and measure and sample macroscopic lesions. c. Use histological methods, including silver stains and immunohistochemistry for tau and Ap to collect standardized pathologic data on all cases. d. Perform immunostaining with antibodies to a-synuclein on all cases. In cases with Lewy bodies, assign a diagnosis according to the Consortium for Dementia with Lewy Bodies. e. Perform immunostaining with antibodies to TDP-43 on all cases, and when positive on the screening section, subtype and map the distribution of TDP-43 pathology. f. Consensus on clinicopathologic diagnoses are made at videoconferences held twice a month. g. Provide neuropathological data to the National Alzheimer Coordinating Center (NACC). 3. Store brain tissue and brain derived material (e.g., DNA) and provide clinically and pathologically well- characterized tissue samples, DNA or data to investigators of ADRC research projects and ADRC pilot projects as well as to qualified outside investigators. RELEVANCE (See instructions): The Neuropathology Core provides a final diagnosis (the"gold standard") for the patients enrolled in the study and is a repository of data and tissue for research purposes. Neuropathologic studies provide quality control and advance understanding of human neurologic disorders with the goals of improving diagnostic accuracy and understanding the cause of these disorders.